Central Heating Room Stat problem

[Marnhullman]

I have an oil fired Boulter Buderas Camray 5 boiler. The central heating system includes a room stat and a Honeywell programmer.

The programmer works OK and I've just replaced the room stat because I thought that was the cause of the boiler not operating as it should but not so.

Even when the room stat is set below the ambient temperature and is therefore in the on position the boiler does not start until I turn the room stat down and then up again I.e. off and then on again.

Is there a component in the boiler to which the room stat is connected that may be faulty e.g. a capacitor that could be dodgy and only works with the extra surge of power that turning the room stat on and off produces?

Thanks.

 

[Terrywookfit]

Which model Camray 5 do you have ??

 

[Marnhullman]

BBJ 95/130

 

[Echo the husky]

Even when the room stat is set below the ambient temperature and is therefore in the on position the boiler does not start until I turn the room stat down and then up again I.e. off and then on again.

I assume you mean when the stat is set above the ambient temperature and is therefore in the on position...

 

[Terrywookfit]

Does the boiler work ok for hot water demands.
Are there any motorised valves.

 

[Marnhullman]

Yes, I meant above the ambient temp!

No the whole boiler is inactive until the stat is turned down then up again. There are two leds on the control panel of the boiler - one to indicate the burner is on and one for mains power and both are off until I turn the stat up and down. There is one motorised valve.

 

[Terrywookfit]

Some information would be useful .
Is system Gravity hot water or fully pumped. How many pipes go to boiler.
2 or 3 port valve.
Does pump run.
Which programmer do you have.
Do you have a multimeter.

If mains neon is not on it is not a boiler problem.

 

[Marnhullman]

Seem to be four pipes. Fully pumped. Two port valve. The pump runs. Honeywell STC6400c programmer. I have a multimeter.

 

[Terrywookfit]

If you turn the programmer to water only......what happens.
Is the m/v energised by the room stat ?
Is there a cylinder stat.
Photos would be good.

 

[Alec_t]

There are two leds on the control panel of the boiler - one to indicate the burner is on and one for mains power and both are off until I turn the stat up and down.

I would have expected the mains power LED to be independent of the roomstat .

 

[Marnhullman]

Thanks for your interest bug I believe we're getting off track. The problem is that although the stat works it's failing to start the boiler.

Can anyone advise as to what component in the boiler the stat is connected or is there no component I.e. just a connection box?

 

[Terrywookfit]

There is only a control stat and limit stat inside the boiler ..Wired in series to turn burner on /off

The power indicator neon is illuminated when there is a supply to boiler.

We are not getting off track.......The problem is external from the boiler.

You seem unwilling to provide any information that helps.

Four pipes sounds like gravity primaries not fully pumped.

If I was on site I would know by looking.

 

[Marnhullman]

I'm pretty sure it's a full-pumped system because we have no roof space so no header tank just a cylinder on the first floor and the boiler on the ground floor. There is a cylinder stat. I don't believe the m/v is energised by the room stat but I'm not knowledgeable enough to be sure.

 

[Terrywookfit]

Where is the pump and m/v relative to the boiler.

AGAIN What happens if you turn heating off at programmer and turn water to on ?

 

[Marnhullman]

The m/v is beside the cylinder in the airing cupboard and the pump is in the boiler housing. The hot water and heating are controlled separately on the Honeywell programmer. If the c/h is off and the h/w is on then the system works OK.